Instructions
Plug in the controllers. One controller for each player must be plugged into the console prior to turning it on.
Turn on the game console and allow "Halo: Combat Evolved" load to the main screen. Open the multiplayer mode from the main menu. Select "Split Screen."
Choose the desired profiles for each character and hit the "A" button to continue. The profile isn't especially important, but some players choose to use the same profile each time.
Choose any map when prompted to do so. Slayer mode can be played on any map. Hit "A" to continue to the "Select Gametype" screen.
Select "Slayer" from the choices and hit "A." A new screen will load with information on the multiplayer game settings. Hit "A" to confirm the settings.